Quiz Electronics Engineering 26 Oct 2020

Quiz Electronics Engineering
Exam: NIC
Topic: Miscellaneous
Date: 26/10/2020

Each Question carries 1 Mark
Negative Marking: 1/4
Time: 10 Minutes

Q1. To deliver a message to the correct application program running on a host, the _______ address must be consulted.
(a) IP
(b) Port
(c) MAC
(d) None of the above

Q2. An a.c series circuit has R = 6 Ω,X_L=20 Ω and X_C=12Ω. The circuit power factor will be
(a) 0.8 Leading
(b) 0.5 Lagging
(c) 0.6 Leading
(d) 0.6 Lagging

Q3. In 8085 to disable the whole interrupt(except TRAP):
(a) the interrupt instruction may be used
(b) the SI instruction may be used.
(c) the DI instruction may be used.
(d) the EI instruction may be used

Q4. The main factor that determines the accuracy of a reconstructed PCM signal is the
(a) number of bits used for quantization
(b) pulse repetition rate
(c) pulse amplitude
(d) Signal bandwidth

Q5. The number 1000_2 is equivalent to decimal number
(a) one thousand
(b) eight
(c) four
(d) sixteen

Q6. Which of the following device has characteristics closed to that of an ideal current source?
(a) Gas diode
(b) Crystal diode
(c) Transistor in CB mode
(d) All of the above

Q7. Which one of the following systems described by the following input-output relations is non-linear?
(a) y(n) = x^2(n)
(b) y(n) = x(n^2)
(c) y(n) = n^2x(n)
(d) y(n) = nx(2n)

Q8. Match List-I(Electromagnetic Law) with List-II(Differential Form) and select the correct answer using codes given below the lists:
List-I List-II
A. Ampere’s Law 1. ∇.D ⃗ = ρ_v
B. Faraday’s Law 2. ∇.J ⃗ = -(∂H ⃗)/∂t
C. Gauss Law 3. ∇ × H ⃗ = J ⃗ + (∂D ⃗)/∂t
D. Current Continuity equation 4. ∇ × E ⃗ = -(∂B ⃗)/∂t
Codes:
A B C D
(a) 1 2 3 4
(b) 3 4 1 2
(c) 1 4 3 2
(d) 3 2 1 4

Q9. Which of the following addressing mode is not usable in XCH instruction of 8085 microprocessor?
(a) Direct Addressing
(b) Indirect Addressing
(c) Immediate Addressing
(d) Register Addressing

Q10. Turn-off time of a thyristor is
(a) depends on load
(b) depends upon junction temperature
(c) depends upon forward current
(d) both (b) and (c)

SOLUTIONS

S1. Ans.(b)
Sol.
IP address tells about the location of the network.
MAC address is a unique address for every device.
Port address identifies a process or service which are to be carried to the device present at the destination.

S2. Ans(d)
Sol.
Z=√(6^2+(20-12)²) = 10
ϕ= R/Z = 6/10 = 0.6 lagging

S3. Ans.(c)
Sol. Destination Index(DI) instruction will disable all the instructions except TRAP.

S4. Ans.(a)
Sol. In PCM signal, quantization noise depends only on the number of bits used for quantization.
Qe = Δ/2 = (Dynamic Range)/(2.2^n )
Therefore, The main factor that determines the accuracy of a reconstructed PCM signal is number of bits used for quantization.

S5. Ans.(b)
Sol. Here,
⇒ 10002 = 2^3 x 1 + 2^2 x 0 + 2^1 x 0 + 2^0 x 0
So, 10002 = 8
Therefore, The number 1000_2 is equivalent to decimal number is 810.

S6. Ans.(c)
Sol. Ideal current source has internal resistance in parallel to it and its value is infinity so that no current could flow through the internal resistance branch and all of the current is supplied to the load.
The output resistance of CB transistor is very high so that no emitter current is lost and current obtained at load of transistor is approx. equal to emitter current.
This characteristics of CB configuration BJT is similar to that of ideal current source. Both can supply all current to the load.

S7. Ans.(a)
Sol. Input-output relation y(n) = x^2(n) does not satisfy the superposition and homogeneity property. If degree of output or input function is other than 1 then system generally behaves as non-linear. Hence, it is non-linear.

S8. Ans.(b)

S9. Ans.(c)

S10. Ans.(d)
Sol: The turn off time of a thyristor is the time between the instant when anode current becomes zero and the instant when the thyristor regains forward blocking capability. So, it depends on the forward current and also junction temperature. During turn off time, excess minority carriers from all the four layers of the thyristor must be removed.

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